CIRCULATION, BLOOD AND uLAXUS <2r,
knee-joint and a genicular trunk, and the latter divide-* into lateral, mesial and descending arteries. The iatera genicular artery gives a nutrient artery to the fer^ir, ,\ branch to the back of the knee-joint and one which passes round to the front of the capsule. The mesial genicular artery supplies the capsule in the popliteal space. The descending isural) artery supplies the popliteus and passes between the tibia and fibula to the anterior tibial muscles, This plan is adopted in the Gorilla, but the genicular and sural branches are more numerous, and there is a recurrent artery in addition.
The posterior tibial artery is generally similar in the Gorilla and Chimpanzee. In the latter it continues the popliteal artery. It gives otf a recurrent branch, which anastomoses with the geniculate arteries, but this vessel arises from the popliteal artery in the Gorilla. It gives off a vessel corresponding to the anterior tibial artery in Man ; this branch runs down in the posterior tibial region and then curves into the anterior tibial region ; and it gives off the following branches :—
(1'i An artery which anastomoses with the saphenous artery to form the arterial arcade on the dorsurn of the foot.
(2) Muscular arteries. Malleolar arteries. Nutrient artery to the fibula.
(5) Articular arteries to the ankle-joint.
The posterior tibial artery divides under the laciniate ligament into medial and lateral plantar arteries. The medial plantar artery gives off medial calcanean branches to the skin of the inner side of the sole, digital arteries to the three inner toes and muscular arteries to the